A U.S. senator wants Apple and Google to require some applications in their mobile app stores to have privacy policies as a way to protect users against location tracking.

Senator Al Franken, a Minnesota Democrat and chairman of the Senate Judiciary Committee's privacy subcommittee, called on the two mobile OS makers to require privacy policies for "location-aware" apps in a letter sent to the CEOs of Apple and Google Wednesday. Neither company requires apps they sell to have privacy policies in place, he said in the letter.

"Apple and Google have each said time and again that they are committed to protecting users' privacy," Franken wrote. "This is an easy opportunity for your companies to put that commitment into action."

A recent study from TRUSTe and Harris Interactive found that less than 20 percent of the 340 top free apps available through mobile networks have links to privacy policies, Franken said.

Franken's letter follows hearings in Congress this month on location tracking on mobile phones. Apple and Google have sent mixed signals on what information they collect about users, Franken said in a May 10 hearing.

"Requiring that each app in your stores have a clear, understandable privacy policy would not resolve most of the privacy concerns in the mobile market," Franken wrote. "But it would be a simple first step that would provide users, privacy advocates, and federal consumer protection authorities a minimum of information about what information an app will access and how that app will share that information with third parties."

Representatives of Google and Apple weren't immediately available for comment.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is grant_gross@idg.com.

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